Triggering on Hard Probes in Heavy-Ion Collisions with the CMS Experiment at the LHC

Studies of heavy-ion collisions at the LHC will benefit from an array of qualitatively new probes not readily available at lower collision energies. These include fully formed jets at ET > 50 GeV, Z0's and abundantly produced heavy flavors. For Pb+Pb running at LHC design luminosity, the collision rate in the CMS interaction region will exceed the available bandwidth to store data by several orders of magnitude. Therefore an efficient trigger strategy is needed to select the few percent of the incoming events containing the most interesting signatures. In this report, we will present the heavy-ion trigger strategy developed for the unique two-layer trigger system of the CMS experiment which consists of a ``Level-1'' trigger based on custom electronics and a High Level Trigger (HLT) implemented using a large cluster of commodity computers.Comment: 4 pages, 1 figure, To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

The Muon Spectrometer of the ALICE experiment

The main goal of the Muon Spectrometer of the ALICE experiment is the measurement of heavy quarks in pp, pA and AA collisions at LHC energies, via the muonic channel. Physics motivations, the apparatus and its physics performances are presented in this talk.Comment: 5 pages, 4 figures. Talk presented in Phase transitions in strongly interacting matter Prague, 23.8.-29.8. 2004 18th Nuclear Physics Division Conference of the EPS (NPDC18) Europhysics Conferenc

INFN What Next: Ultra-relativistic Heavy-Ion Collisions

This document was prepared by the community that is active in Italy, within INFN (Istituto Nazionale di Fisica Nucleare), in the field of ultra-relativistic heavy-ion collisions. The experimental study of the phase diagram of strongly-interacting matter and of the Quark-Gluon Plasma (QGP) deconfined state will proceed, in the next 10-15 years, along two directions: the high-energy regime at RHIC and at the LHC, and the low-energy regime at FAIR, NICA, SPS and RHIC. The Italian community is strongly involved in the present and future programme of the ALICE experiment, the upgrade of which will open, in the 2020s, a new phase of high-precision characterisation of the QGP properties at the LHC. As a complement of this main activity, there is a growing interest in a possible future experiment at the SPS, which would target the search for the onset of deconfinement using dimuon measurements. On a longer timescale, the community looks with interest at the ongoing studies and discussions on a possible fixed-target programme using the LHC ion beams and on the Future Circular Collider.Comment: 99 pages, 56 figure

LHC Expectations (Machine, Detectors and Physics)

Starting in two years from now, particle physics will enter a new regime in terms of energies and luminosities, thanks to the Large Hadron Collider (LHC) at CERN. This report summarizes the status of the preparations, both for the machine and the detectors, as of fall 2005. The commissioning and start-up scenarios are outlined and some highlights from the very rich physics programme are given, concentrating on measurements of Standard Model processes, as well as on early discovery scenarios. The prospects of B-physics and heavy ion collisions at LHC are also briefly discussed. The report concludes with an outlook on the ultimate physics reach and on upgrade scenarios.Comment: Plenary talk given at the International Europhysics Conference on High Energy Physics, July 21st - 27th 2005, Lisboa, Portuga

Relativistic heavy-ion physics

The study of relativistic heavy-ion collisions is an important part of the LHC research programme at CERN. This emerging field of research focuses on the study of matter under extreme conditions of temperature, density, and pressure. Here we present an introduction to the general aspects of relativistic heavy-ion physics. Afterwards we give an overview of the accelerator facility at CERN and then a quick look at the ALICE project as a dedicated experiment for heavy-ion collisions.Comment: 23 pages, Lectures given at the 5th CERN-Latin-American School of High-Energy Physics, Recinto Quirama, Colombia, 15 - 28 Mar 200

Jet measurements in the ALICE experiment at the LHC

Jet tomography probes provide a means to explore the properties of highly compressed and excited nuclear matter created in heavy ion collisions. The capabilities of the ALICE experiment, with its electromagnetic calorimeter (EMCal) upgrade, to trigger on and reconstruct jets in p+p and Pb+Pb collisions at $\sqrt{s_{NN}}$=5.5 TeV are presented.Comment: 8 pages, 6 figures. Presented at the IX International Conference on Nucleus-Nucleus Collisions, Rio de Janeiro, Brazil, August 28 - September 1, 200

Photoproduction at collider energies: from RHIC and HERA to the LHC

We present the mini-proceedings of the workshop on ``Photoproduction at collider energies: from RHIC and HERA to the LHC'' held at the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento) from January 15 to 19, 2007. The workshop gathered both theorists and experimentalists to discuss the current status of investigations of high-energy photon-induced processes at different colliders (HERA, RHIC, and Tevatron) as well as preparations for extension of these studies at the LHC. The main physics topics covered were: (i) small-$x$ QCD in photoproduction studies with protons and in electromagnetic (aka. ultraperipheral) nucleus-nucleus collisions, (ii) hard diffraction physics at hadron colliders, and (iii) photon-photon collisions at very high energies: electroweak and beyond the Standard Model processes. These mini-proceedings consist of an introduction and short summaries of the talks presented at the meeting

Heavy Ion physics with the ALICE experiment at the CERN LHC

After close to 20 years of preparation, the dedicated heavy ion experiment ALICE took first data at the CERN LHC accelerator with proton collisions at the end of 2009 and with lead nuclei at the end of 2010. After a short introduction into the physics of ultra-relativistic heavy ion collisions, this article recalls the main design choices made for the detector and summarizes the initial operation and performance of ALICE. Physics results from this first year of operation concentrate on characterizing the global properties of typical, average collisions, both in pp and nucleus-nucleus reactions, in the new energy regime of LHC. The pp results differ, to a varying degree, from most QCD inspired phenomenological models and provide the input needed to fine-tune their parameters. First results from Pb-Pb are broadly consistent with expectations based on lower energy data, indicating that high density matter created at LHC, while much hotter and larger, still behaves like a very strongly interacting, almost perfect liquid.Comment: Talk given at Royal Society meeting on "Physics at the high energy frontier - the Large Hadron Collider project", London, 16 - 17 May 2011, to be published in "Philosophical Transactions of the Royal Society A